One of the most important areas contributing to the overall performance of a sewing machine is the stitch tongue area of the sewing machine throat plate. Because the stitch tongue area of the throat plate is intimately involved with the formation of the stitch, its concise fabrication is paramount to the overall performance of the machine. Also, to allow continued and effective use of a sewing machine in the sewing plant, throat plates must be readily replaceable. Thus, the thousands of like throat plates being produced and used every year must also be consistent to allow interchangeability.
To meet the stringent requirements of conciseness and consistency previously required tedious hours of hand labor in producing the throat plate. Even with hand worked throat plates, consistency between parts remained a difficult standard to meet. That is, one plate could vary from the next depending upon the experience and expertise of the craftsperson producing the plate. Recently, some manufacturers have turned to alloyed steels in an effort to improve the durability of the throat plates. Although alloyed steels may produce stronger throat plates, there are a number of drawbacks associated with throat plates made from alloyed steels. Alloyed steels require increased machining time to produce the desired stitch tongue. Also, alloyed steels result in increased tool wear used in forming the throat plate. Even though more durable, the requirements of consistency and conciseness are not guaranteed by using alloyed steels.